Etching reagent, and method for manufacturing electronic device substrate and electronic device

ABSTRACT

The present invention provides an etching agent that is able to etch a Cu film by a simple chemical etching method such as an immersion method when the low resistance Cu film is used for a wiring material, while allowing time-dependent changes of the etching rate to be small and preventing a pattern narrowing phenomenon ascribed to irregular amount of side etching of the Cu film from occurring, by providing an etching agent comprising an aqueous solution containing potassium hydrogen peroxosulfate and hydrofluoric acid, wherein masks of a give pattern is formed on the surface of a laminated film prepared by sequentially depositing a Ti or Ti alloy film and a Cu film on a substrate, and wherein a gate electrode (a laminated wiring) and a lower pad layer (a laminated wiring) with give patterns are formed by etching the laminated film using the etching agent having the foregoing construction.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an etching reagent for manufacturing awiring using low resistance copper, and a method for manufacturing anelectronic device substrate and an electronic device.

2. Description of the Related Art

An example of electronic devices comprises a thin film transistor typeliquid crystal display device.

FIG. 9 is an illustrative drawing of the conventional thin filmtransistor type liquid crystal display device.

A gate electrode 84 comprising a conductive material such as Al or an Alalloy is provided on a substrate 83 of this thin film transistor 82, anda gate insulation film 85 is provided so as to cover the gate electrode84. A semiconductor active film 86 comprising an amorphous silicon(abbreviated as a-Si hereinafter) is provided on the gate insulationfilm 85 above the gate electrode 84, and a source electrode 88 and adrain electrode 89 comprising a conductive material such as Al or an Alalloy are provided via an ohmic contact layer 87 comprising an amorphoussilicon containing a N-type impurity such as phosphorus (abbreviated asa N⁺-type a-Si hereinafter) from the semiconductor active film 86through the gate insulation film 85. A passivation film 90 is providedso as to cover the thin film transistor 82 composed of these sourceelectrode 88, drain electrode 89, gate electrode 84 and the like, and acontact hole 91 is provided through the passivation film 90 on the drainelectrode 89. A pixel electrode 92 comprising a transparent electrodelayer comprising indium tin oxide (abbreviated as ITO hereinafter) thatis electrically connected to the drain electrode 89 trough the contacthole 91 is additionally provided.

The left portion of FIG. 9 shows a cross sectional structure of a gateterminal pad portion 93 at the end of the gate wiring located at outsideof the display area. A contact hole 95 perforating through the gateinsulation film 85 and passivation film 90 is provided on a lower padlayer 94 comprising a gate wiring material such as Al or an Al alloy onthe substrate 83. An upper pad layer 96 comprising a transparentelectrode layer, which is electrically connected to the lower pad layer94 through the contact hole 95, is also provided.

The problem of retardation of signal transmission due to the resistanceof electrodes such as the gate electrodes, source electrode, and drainelectrode, and the resistance of wiring such as the gate wiring, sourcewiring and drain wiring have became apparent in compliance with therecent development of the high speed liquid crystal display device.Accordingly, use of copper having a lower resistance than that of Al oran Al alloy has been studied for solving the problems as describedabove. The materials constituting the electrode such as the gateelectrode are also included in the wiring materials herein.

A Cu wiring can be formed, like constructing a wiring with Al or an Alalloy, by the steps comprising: forming a Cu film by a conventionalsputtering method, forming a given mask pattern on the surface of the Cufilm by photolithography, etching the Cu film using a given etchingagent, and removing the Cu film except the area for forming the wiring.

The etching agents for Cu known in the art comprise PAN based(phosphoric acid-acetic acid-nitric acid based) etching agents, andammonium peroxosulfate and acetic acid-hydrogen peroxide based etchingagents, which have been frequently used for the etching agent for use infine processing.

However, when a mask pattern 84b as shown in FIG. 10A, formed on thesurface of a Cu film 84 a deposited on a substrate 83 a for forming awiring, is subjected to etching by immersing it in an ammoniumperoxosulfate based or PAN based etching agent in a stationary state,the Cu film 84 a at the periphery of the mask pattern 84 b is etchedwith an abnormally high etching rate to increase the amount of etchingat the central portion at the side faces of the Cu film 84 a more thanthe amount of etching at the remaining portions. As a result, the linewidth of the wiring 84 c turns out to be narrower than the width of themask pattern 84 b (slimming phenomenon of the pattern) as shown in FIG.

When a mixed solution of acetic acid and hydrogen peroxide or a ammoniumperoxosulfate solution is used as an etching agent, it is difficult tocontrol the immersion time of the Cu film since the etching rate isvigorously changed with time, thereby making it difficult to obtain a Cuwiring having a desired line width. However, the slimming phenomenon asdescribed above is not observed when the acetic acid-hydrogen peroxidebased etching agent is used.

SUMMARY OF THE INVENTION

Accordingly, the object of the present invention carried out in view ofthe foregoing circumstances is to provide an etching agent that enablesthe Cu film to be etched by a simple chemical etching method such as astationary immersion method for using a low resistance Cu film as awiring material with little time dependent change of the etching rate,besides preventing the pattern slimming phenomenon caused by irregularamount of etching at the side face of the Cu film (the amount of sideetching).

In a first aspect, the present invention for solving the problems ashitherto described provides an etching agent for copper comprising anaqueous solution containing potassium hydrogen peroxomonosulfate.

According to the etching agent having such construction as describedabove, the Cu film may be etched by a simple chemical etching methodsuch as a stationary immersion method, besides allowing a copper wiringwith a desired line width since the etching rate shows no time-dependentchanges of the etching rate, and the amount of side-etching of the Cufilm is uniform.

The etching agent for copper as described above may contain acetic acid.The etching agent as described above shows no time-dependent changes ofthe etching rate, and the amount of side-etching of the Cu film isuniform besides being improved in wettability on the copper film,thereby enabling a copper wiring having an excellent dimensionalaccuracy to be formed even when a fine copper wiring is to be formed.

Preferably, the concentration of potassium hydrogen peroxomonosulfatefalls within a range of 0.08 to 2.0 mol/l, more preferably within arange of 0.1 to 1.0 mol/l. When the concentration of potassium hydrogenperoxomonosulfate is less than 0.08 mol/l, only the copper film at theperiphery of the mask pattern is so abnormally rapid etching rate thatthe line width of the copper wiring obtained turns out to be narrowerthan the width of the mask pattern. When the concentration of potassiumhydrogen peroxomonosulfate exceeds 2.0 mol/l, on the other hand, etchingrate becomes too rapid that the line width of the copper wiring may behardly controlled.

In accordance with another aspect of the present invention, the etchingagent for a laminated film of a titanium film and a copper filmcomprises an aqueous solution containing potassium hydrogenperoxomonosulfate and hydrofluoric acid. According to the etching agentas described above, the side faces of the copper film constituting thelaminated film may be uniformly etched besides enabling the titanium ortitanium alloy film and the copper film to be collectively etched by asimple chemical etching method such as a stationary immersion method.

In one aspect, the etching agent for a laminated film of a molybdenumfilm and a copper film comprises an aqueous solution containingpotassium hydrogen peroxomonosulfate, phosphoric acid and nitric acid.The side faces of the copper film constituting the laminated film can beuniformly etched using the etching agent as described above, besidesallowing both of the molybdenum or molybdenum alloy film and the copperfilm to be collectively etched by a simple chemical etching method suchas a stationary immersion method.

In another aspect, the etching agent for a laminated film of a chromiumfilm and a copper film comprises an aqueous solution containingpotassium hydrogen peroxomonosulfate and hydrochloric acid. The sidefaces of the copper film constituting the laminated film can beuniformly etched using the etching agent as described above, besidesallowing both of the chromium or chromium alloy film and the copper filmto be collectively etched by a simple chemical etching method such as astationary immersion method.

The etching agent for a laminated film of a titanium film and a copperfilms may comprise an aqueous solution containing a peroxosulfate salt,hydrofluoric acid, and hydrochloric acid or a chloride. When the etchingagent as described above is used for etching the laminated film of thetitanium film and copper film, the lamination film can be collectivelyetched without leaving any etching residues besides enabling a laminatedwiring to be precisely formed with a desired line width, therebyallowing the manufacturing process to be simple and the manufacturingyield to be improved.

When the Cl concentration (Cl⁻ ion concentration) in the etching agentcomprising an aqueous solution containing a peroxosulfate salt andhydrochloric acid or a chloride is increased, the etching rate isenhanced while reducing the amount of the etching residues. However, theupper limit of the Cl concentration is preferably about 10% because,when the Cl concentration is too large, the etching rate turns out to beso rapid that the etching rate may be hardly controlled.

The etching agent for a laminated film of a titanium film and a copperfilms may comprise an aqueous solution containing a potassiumperoxosulfate salt and a fluoride. Since fluorine contained in thefluoride exists as F⁻ ions in the aqueous solution when the etchingagent as described above is used, the laminated film of the titanium ortitanium alloy film and the copper film can be collectively etchedwithout leaving any etching residues to allow a laminated wiring to beaccurately formed with a desired line width, even when the etching agentdoes not contain HF. Therefore, the manufacturing process can besimplified besides improving the manufacturing yield. The etching agentmay contain hydrofluoric acid.

The peroxosulfate salt to be used may comprise any one or more compoundsselected from KHSO₅, NaHSO₅, K₂S₂O₈, Na₂S₂O_(8 and (NH) ₄)₂S₂O₈.

Preferably, the chloride comprises an alkali metal chloride or ammoniumchloride, examples of them being KCl, NaCl and NH₄Cl.

Preferably, the fluoride comprises an alkali metal fluoride or ammoniumfluoride, examples of them being KF, NaF and NH₄F.

A preferable combination of the peroxosulfate salt and the chloride formaking the etching agent to contain one kind of cation comprises, forexample, the combination of KHSO₅ and KCl and the combination of(NH₄)₂S₂O_(8 and NH) ₄Cl. A preferable combination of the peroxosulfatesalt and the fluoride comprises, for example, the combination of KHSO₅,and KF, and the combination of (NH₄)₂S₂O_(8 and NH) ₄F.

In accordance with a further aspect of the present invention, thepresent invention provides a method for manufacturing an electronicdevice substrate comprising the steps of: depositing a copper film on asubstrate; forming a mask of a given pattern on the surface of thecopper film; and etching the copper film using an etching agent,comprising an aqueous solution containing potassium hydrogenperoxomonosulfate and having any one of the constitutions describedabove, to form a copper wiring with a given pattern.

Since the method for manufacturing the electronic device substrate withconstructions as described above has such advantages as making itpossible to etch the Cu film by a simple chemical etching method such asa stationary immersion method. In addition, the time dependent change ofthe etching rate is small, and the side faces of the Cu film can beuniformly etched (the amount of side etching is uniform) to allow thecopper wiring to be formed with a desired line width with good yield.Moreover, the manufacturing process is simple with an improvedmanufacturing efficiency. Accordingly, it is possible to obtain anelectronic device substrate with low cost by improving the manufacturingyield according to the method for manufacturing the electronic devicesubstrate having the constructions as described above.

In accordance with a different aspect, the present invention provides amethod for manufacturing an electronic device substrate comprising thesteps of: forming a mask with a given pattern on a laminated filmprepared by sequentially depositing a titanium or a titanium alloy filmand a copper film on a substrate; and etching the laminated filmcomprising the titanium or titanium alloy film and the copper film usingthe etching agent having any one of the constructions as described aboveaccording to the present invention to form a laminated wiring with agiven pattern.

According to the method for manufacturing the electronic devicesubstrate having the constructions as described above, the side faces ofthe copper film constituting the laminated film may be uniformly etched,and both of the titanium or titanium alloy film and the copper filmconstituting the laminated film may be collectively etched by a simplechemical etching method such as an immersion method. Therefore, themanufacturing yield becomes high and the manufacturing process may beshortened. Consequently, an electronic device substrate can be obtainedwith a low manufacturing cost according to the method for manufacturingthe electronic device substrate having the constructions as describedabove by improving the manufacturing yield and manufacturing efficiency.

When an aqueous solution containing a peroxosulfate salt, hydrofluoricacid and hydrochloric acid or a chloride, or an aqueous solutioncontaining a peroxosulfate salt and a fluoride is particularly used forthe etching agent, the laminated film of the titanium or titanium alloyfilm and the copper film can be collectively etched without leaving anyetching residues to allow a laminated wiring with a desired line widthto be accurately formed, thereby making it possible to simplify themanufacturing process besides improving the manufacturing yield.

In a further different aspect, the present invention provides a methodfor manufacturing an electronic device substrate comprising at least afirst metallic layer, a first insulation layer, a semiconductor layer, asecond metallic layer and a second insulation layer, wherein the methodfor depositing at least one of the first and second metallic layerscomprises the steps of: forming a mask of a given pattern on the surfaceof a laminated film prepared by sequentially depositing a titanium ortitanium alloy film and a copper film; and etching the laminated film ofthe titanium or titanium alloy film and the copper film using an etchingagent comprising an aqueous solution containing a peroxosulfate salt,hydrofluoric acid and hydrochloric acid or a chloride, or an etchingagent comprising an aqueous solution containing a peroxosulfate salt anda fluoride, to form a laminated wiring with the given pattern asdescribed above.

According to the method for manufacturing the electronic devicesubstrate having the constructions as described above, the laminatedfilm of the titanium or titanium alloy film and the copper film can becollectively etched without leaving any etching residues to enable alaminated wiring to be precisely formed with a desired line width,thereby allowing the manufacturing process to be simplified besidesimproving the manufacturing yield.

The semiconductor layer described above may be formed of polysilicon inthe method for manufacturing the electronic device substrate.

The electronic device according to the present invention comprises asubstrate manufactured by the method for manufacturing the electronicdevice substrate having any one of the foregoing constructions.

Since the electronic device having the constructions as described aboveis provided with a laminated wiring comprising copper films or alaminated wiring having a copper film as a low resistance wiring,decrease of signal voltages or signal retardation in the wiring ascribedto the wiring resistance is hardly caused, making it easy to construct adisplay device appropriate for large area display in which the wiringlength is increased or for high precession display in which fine wiringis required.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates the first step of the method for manufacturing thethin film transistor substrate in the first embodiment of the method formanufacturing the electronic device substrate according to the presentinvention.

FIG. 1B illustrates the second step of the method for manufacturing thethin film transistor substrate in the first embodiment of the method formanufacturing the electronic device substrate according to the presentinvention.

FIG. 1C illustrates the third step of the method for manufacturing thethin film transistor substrate in the first embodiment of the method formanufacturing the electronic device substrate according to the presentinvention.

FIG. 1D illustrates the fourth step of the method for manufacturing thethin film transistor substrate in the first embodiment of the method formanufacturing the electronic device substrate according to the presentinvention.

FIG. 2A illustrates the first step of the method for manufacturing thethin film transistor substrate in the first embodiment of the method formanufacturing the electronic device substrate according to the presentinvention.

FIG. 2B illustrates the second step of the method for manufacturing thethin film transistor substrate in the first embodiment of the method formanufacturing the electronic device substrate according to the presentinvention.

FIG. 3 shows a partial cross section of the thin film transistorsubstrate obtained in the first embodiment of the method formanufacturing the electronic device substrate according to the presentinvention.

FIG. 4 shows a partial cross section of the thin film transistorsubstrate manufactured in the fourth embodiment of the method formanufacturing the thin film transistor substrate according to thepresent invention.

FIG. 5 shows an illustrative drawing of one example of the reflectiontype liquid crystal display having the thin film transistor substratemanufactured by the method for manufacturing the thin film transistorsubstrate in any of the first to fifth embodiments according to thepresent invention.

FIG. 6 shows the mole concentration dependency of the etching rate of Cuwhen the Cu film is etched using the etching agent in the example and inthe comparative example.

FIG. 7 shows the film thickness distribution of the Cu film when the Cufilm is etched using the etching agent in the example and in thecomparative example.

FIG. 8 shows the time-dependent change of the etching rate when the Cufilm is etched using the etching agent in the example and in thecomparative example.

FIG. 9 is an illustrative drawing showing the thin film transistorportion of the conventional thin film transistor type liquid crystaldisplay device.

FIG. 10A shows an illustrative drawing of the first step of the methodfor manufacturing the conventional electronic device substrate.

FIG. 10B shows an illustrative drawing of the second step of the methodfor manufacturing the conventional electronic device substrate.

FIG. 11 shows a partial cross section of the thin film transistorsubstrate obtained by the method for manufacturing the electronic devicesubstrate according to the fourth embodiment of the present invention.

FIG. 12 is a graph showing the HCl concentration dependency of theetching depth of the Cu monolayer film when the HCl concentration in theetching agent is changed within a range of 0% to 0.5%.

FIG. 13 is a graph showing the HCl concentration dependency of theetching-off time of the Ti monolayer film when the HCl concentration inthe etching agent is changed within a range of 0% to 0.5%.

FIG. 14 is a graph showing the HCl concentration dependency of theetching-off time of the laminated film comprising the Ti film and the Cufilm when the HCl concentration in the etching agent is changed within arange of 0% to 0.5%.

FIG. 15 is a graph showing the KF or NH₄F concentration dependency ofthe etching-off time of the laminated film comprising the Ti film andthe Cu film when the KF or NH₄F concentration in the etching agent ischanged within a range of 0% to 0.5%.

FIG. 16 is a graph showing the relations between the etching time andthe etching depth of the Cu monolayer film when the KF concentration inthe etching agent is changed within a range of 0.1% to 0.5%, and when0.2% HF is used instead of KF.

DESCRIPTION OF THE PREFERRED EMBODIMENT

While the present invention is described in detail hereinafter withreference to the drawings, the present invention is not restricted tothese embodiments.

First Embodiment

FIG. 3 is a partial cross section showing an example of the thin filmtransistor substrate manufactured by applying the method formanufacturing the electronic device substrate according to the presentinvention to a method for manufacturing a thin film transistor substrate(the method for manufacturing the thin film transistor substrateaccording to the first embodiment) provided in a liquid crystal displaydevice.

The portions with reference marks a, b and c denote a thin filmtransistor portion (TFT), a terminal portion of a source wiring locatedat outside of a TFT matrix and a terminal portion of a gate wiring,respectively. Although these three portions are located with somedistances apart in the actual liquid crystal device provided with thisthin film transistor substrate 1, and they can not be naturallyexhibited simultaneously in the drawing, they are illustrated as if theyare in adjacent relations one another for the convenience ofillustration.

The thin film transistor portion a will be described first.

A gate electrode 5 comprising a Ti or Ti alloy film 3 with a filmthickness of about 50 to 100 nm and a Cu film 4 with a film thickness ofabout 100 to 200 nm is provided on a substrate 2 of the thin filmtransistor portion a. A gate insulation film 7 is provided on the gateelectrode 5, a semiconductor film 8 comprising an amorphous silicon(a-Si) is provided on the gate insulation film 7, a n⁺-type a-Si layer 9is provided on the semiconductor film 8, and a source electrode 12 and adrain electrode 14 are provided on the n⁺-type a-Si layer 9. The sourceelectrode 12 and the drain electrode 14 comprise a Ti or Ti alloy film.10 with a film thickness of about 50 to 100 nm, a Cu film 11 with a filmthickness of 100 to 200 nm, and a Ti or Ti alloy film 10 with a filmthickness of about 50 to 100 nm.

A passivation film (an insulation film) 17 covering the source electrode12 and the drain electrode 14 is formed above them, and a contact hole18 that reaches the Ti or Ti alloy film 10 provided above the copperfilm 11 is formed through the passivation film 17. Examples of thepassivation film 17 include films of a (amorphous) −SiN_(x):H, a-SiNx,a-SiO₂:H and SiO₂.

An ITO layer 19 to serve as a pixel electrode is formed along the innerwall face and bottom face of the contact hole 18. The drain electrode 14is electrically connected to the ITO layer (the pixel electrode) 19through the contact hole 18.

With respect to the terminal portion b of the source wiring, a lower padlayer 16 a comprising the Ti or Ti alloy film 10, Cu film 11 and Ti orTi alloy film 10 is formed on the gate insulation film 7, thepassivation film 17 is formed on the lower pad layer 16 a, and a contacthole 20 reaching the Ti or Ti alloy film 10 provided on the Al or Alalloy film 11 is formed.

An upper pad layer 21 comprising ITO is formed along the inner wall faceand bottom face of the contact hole 20. The lower pad layer 16 a iselectrically connected to the upper pad layer 21 through the contacthole 20.

With respect to the terminal portion c of the gate wiring, a lower padlayer 16 b comprising the Ti or Ti alloy film 3 and the Cu film 4 isformed on the substrate 2, the gate insulation film 7 is formed on thelower pad layer 16 b, the passivation film 17 is further formed on thegate insulation film 7, and a contact hole 22 reaching the Cu film 4 isformed. An upper pad layer 23 comprising ITO is formed along the innerside wall face and bottom face of the contact hole 22. The lower padlayer 16 b is electrically connected to an upper pad layer 23 throughthe contact hole 22.

The method for manufacturing the thin film transistor substrate in thefirst embodiment according to the present invention will be describedhereinafter with reference to FIGS. 1A to 1D and FIGS. 2A and 2B.

In FIGS. 1A to 1D and FIGS. 2A and B, the portions with reference marksa, b and c denote a thin film transistor (TFT) part, a terminal portionof a source wiring located at outside of a TFT matrix, and a terminalportion of a gate wiring, respectively.

As shown in FIGS. 1A to 1D, a lamination film is formed by sequentiallydepositing a Ti or Ti alloy film 3 and a Cu film 4 on a substrate 2.

With respect to the thin film transistor portion a, after forming a maskpattern 27 with a given pattern by a photolithographic method on the Cufilm 4 constituting the laminated film, the laminated film iscollectively etched using an etching agent comprising potassium hydrogenperoxomonosulfate (KHSO₅) and hydrofluoric acid to form a gate electrode5 comprising the Ti alloy film 3 and the Cu film 4 as shown in FIG. 1B.The concentration of potassium hydrogen peroxosulfate in the etchingagent used herein is preferably within the range of 0.08 to 2.0 mol/l.It is also preferable that the concentration of hydrofluoric acidrelative to potassium hydrogen peroxosulfate in the etching agent isadjusted to be within the range of 0.05 to 2.0 mol/l, in order to enablerespective metallic films constituting the laminated film to be etchedwith approximately the same etching rate in one etching run. The etchingagent preferably contains acetic acid in order to improve wettabilityagainst the laminated film, wherein the weight ration of acetic acidrelative to potassium hydrogen peroxosulfate is preferably adjusted tobe within the range of 10 to 75% by weight.

With respect to the terminal portion c of the gate wiring, the lower pad16 b comprising the Ti or Ti alloy film 3 and Cu film 4 as shown in FIG.1B is formed, after forming a mask pattern 28 with a given pattern byphotolithography on the Cu film 4 constituting the laminated film, bycollectively etching the laminated film using the same etching agent asused in the foregoing example.

The method as described above allows the side face of the Cu film 4constituting the laminated film to be uniformly etched besides enablingboth of the Ti or Ti alloy film 3 and the Cu film 4 to be simultaneouslyetched by a simple chemical etching method such as a stationaryimmersion method.

Then, the gate insulation film 7 is formed over the entire surface ofthe substrate 2 using a CVD method. With respect to the thin filmtransistor portion a, the semiconductor layer 8 and n⁺-type a-Si layer 9are formed, followed by etching the semiconductor layer 8 and n⁺-typea-Si layer 9 as shown in FIG. 1C so as to leave the upper portion ofgate electrode 5 that serves as a channel portion of the TFT behind.

With respect to the thin layer transistor portion a and the terminalportion b of the source wiring, a laminated film is formed bysequentially laminating the Ti or Ti alloy film 10, the Cu film 11 andthe Ti or Ti alloy film 10 as shown in FIG. 1D.

With respect to the thin film transistor portion a, a mask pattern 37with a give pattern is formed on the Ti or Ti alloy film 10 in thelaminated film located at above the gate electrode 5 that serves as achannel part of the TFT by photolithography, followed by forming thesource electrode 12 comprising the Ti or Ti alloy film 10, the Cu film11 and the Ti or Ti alloy film 10 as shown in FIG. 2A, and the drainelectrode 14 by collectively etching the laminated film using the sameetching agent as used in the foregoing example.

With respect to the terminal portion b of the source wiring, a maskpattern 38 with a given pattern is formed on the Ti or Ti alloy film 10of the laminated film by photolithography, followed by collectivelyetching the laminated film using the same etching agent as used in theforegoing example to form the lower pad layer 16 a comprising the Ti orTi alloy film 10, the Cu film 11 and the Ti or Ti alloy film 10 as shownin FIG. 2A.

The method as described above allows the amount of side etching of theCu film 11 constituting the laminated film to be uniform, besidesallowing the Cu film 11 as well as the Ti or Ti alloy film 10 on theupper and lower face of the Cu film to be simultaneously etched by asimple chemical etching method such as a stationary immersion method.

The channel 24 is formed thereafter by etching the n⁺-type a-Si layer 9using a dry method or using a dry method and wet method together.

With respect to the thin film transistor portion a, the terminal portionb of the source wiring and the terminal portion c of the gate wiring,the passivation film 17 is formed on the Ti or Ti alloy films 3 and 10.

With respect to the thin film transistor portion a, the contact hole 18is formed through the passivation film 17 by the dry method or by usingthe dry method and wet method together as shown in FIG. 2B, followed byforming the ITO layer 19 on the bottom face and inner wall face of thecontact hole 18 up to on the upper face of the passivation film 17 asshown in FIG. 3 by patterning after forming the ITO layer over theentire surfaces.

Similarly with respect to the terminal portion b of the source wiringand the terminal portion c of the gate wiring, the contact holes 20 and22 are formed by etching the passivation film 17 by the dry method orusing the dry method and wet method together (the contact hole 22 isformed in the terminal portion c of the gate wiring by etching thepassivation film 17 as well as the gate insulation film 7), followed byforming the upper pad layers 21 and 23 on the bottom faces and innerwall faces of the contact holes 20 and 22 up to on the upper face of thepassivation film 17 by patterning after forming the ITO layer over theentire surface. The thin film transistor substrate 1 as shown in FIG. 3is manufactured by the procedure as described above.

In the method for manufacturing the thin film transistor substrateaccording to the first embodiment, the side faces of the copper films 4and 11 constituting the laminated film can be uniformly etched by usingan etching agent comprising an aqueous solution containing potassiumhydrogen peroxosulfate (KHSO₅) and hydrofluoric acid, when the gateelectrode 5, the source electrode 12, the drain electrode 14 and thelower pad layers 16 a and 16 b are formed by etching the laminated filmformed by sequentially depositing the Ti or Ti alloy film 3 and the Cufilm 4, and the laminated film formed by depositing the Ti or Ti alloyfilms 10 on the upper and lower faces of the Cu film 11. Moreover, sinceboth of the Ti or Ti alloy film 3 and the copper film 4 constituting thelaminated film can be collectively etched by a simple chemical etchingmethod such as a stationary immersion method, or the Cu film 11 and theTi or Ti alloy films 10 formed on the upper and lower faces of thecopper film can be simultaneously etched when the laminated filmcomprises three layers, a good manufacturing yield can be obtained andthe manufacturing process can be shortened. According to the method formanufacturing the thin film transistor in the first embodiment havingthe constructions as hitherto described, a low cost thin film transistorcan be obtained by improving the manufacturing yield and themanufacturing efficiency.

Diffusion of elements into the laminated film may be blocked by the Tior Ti alloy film even when the elements diffuse from adjoining films atthe lower side of the laminated film, because the Ti or Ti alloy film isused at the lower layer of the copper film, thereby allowing increase ofthe wiring resistance ascribed to diffusion of the elements from theadjoining films to be prevented. For example, when the substrate 2 ismade of a glass, Si in the glass substrate is prevented from invadinginto the copper film 4 for forming the gate electrode 5 and the lowerpad layer 16 b, thereby preventing increase of the wiring resistanceascribed to invasion of Si into the copper film 4.

Since the laminated film in which the Ti or Ti alloy film 10 is providedas an upper layer of the copper film 11 is used, anti-oxidative propertyagainst moisture and oxygen in the air, and corrosion resistance againsta resist peeling solution may be improved. Consequently, the sourceelectrode 12, the drain electrode 14 and the lower pad layer 16 a arehardly damaged, enabling peeling of these electrodes 12 and 14 and thelower pad layer 16 a from the substrate, as well as occurrence ofmalfunctioning such as wiring breakage, to be prevented. In addition,since Cu atoms in the copper layer 11 are blocked from diffusing intothe adjoining films by the Ti or Ti alloy film 10, poor insulationresistance ascribed to diffusion of the Cu atoms from the copper layer11 as well as deterioration of characteristics of the semiconductoractive films can be prevented. Diffusion of the elements from theadjoining films at above the laminated film into the electrodes 12 and14 and the lower pad layer 16 a can be also blocked by the Ti or Tialloy film 10, thereby allowing increase of the wiring resistanceascribed to diffusion of the elements from the adjoining films to beprevented.

The technical scope of the present invention is not restricted to theembodiment as hitherto described, but various modifications with respectto the film thickness of the Cu film, the Ti or Ti alloy film, and thepassivation film, and their shapes, are possible within a range notdeparting from the spirit of the present invention.

While the gate electrode 5 and the lower pad layer 16 b have been formedby collectively etching together with the Ti or Ti alloy film 3 and theCu film 4 in the foregoing embodiment, a three-layered film comprisingthe Ti or Ti alloy films formed on the upper and lower faces of the Cufilm may be collectively etched.

While the source electrode 12, the drain electrode 14 and the lower padlayer 16 a have been formed by collectively etching the three-layeredlaminated film comprising the Ti or Ti alloy films formed on the upperand lower faces of the Cu film, they may be formed by collectivelyetching the two-layered laminated film in which the Cu film is formed onthe Ti or Ti alloy film.

While an aqueous solution containing potassium hydrogen peroxosulfateand hydrofluoric acid has been used as the etching agent for thelaminated film in the foregoing embodiment, only the Cu film can beselectively etched by etching the laminated film using an etching agentcomprising an aqueous solution containing potassium hydrogenperoxosulfate, wherein the etching treatment may be applied using anetching agent for the Ti or Ti alloy film prior or after etching the Cufilm.

An aqueous solution containing a peroxosulfate salt, hydrofluoric acid,and hydrochloric acid or a chloride, or an aqueous solution containing aperoxosulfate salt and a fluoride may be used as the etching agent forthe laminated film comprising the Ti or Ti alloy film and the Cu film,instead of using the aqueous solution containing hydrogen potassiumperoxosulfate and hydrofluoric acid as described above. Using suchetching agents allows the laminated film to be collectively etchedwithout leaving any etching residues while enabling the laminated wiringto be precisely formed with a desired line width, thereby making itpossible to simplify the manufacturing process besides improving themanufacturing yield.

Second Embodiment

The method for manufacturing the thin film transistor substrateaccording to the second embodiment of the present invention will bedescribed hereinafter.

The method for manufacturing the thin film transistor substrateaccording to the second embodiment differs from the method formanufacturing the thin film transistor substrate according to the firstembodiment in that a laminated film of a Mo or Mo alloy film and Cu filmis formed for the laminated film for forming the gate electrode 5 andthe lower pad layer 16 b, and a laminated film provided with the Mo orMo alloy films on the upper and lower faces of the Cu film is formed forforming the source electrode 12, the drain electrode 14 and the lowerpad layer 16 a. An aqueous solution containing potassium hydrogenperoxomonosulfate, phosphoric acid and nitric acid is used for theetching agent for these laminated films.

It is preferable for allowing respective metallic films constituting thelaminated film to be etched in one etching run with an approximately thesame etching rate one another, that the concentration of phosphoric acidin the etching agent relative to hydrogen potassium peroxosulfate isadjusted to be within the range of 0.8 to 8 mol/l, and the concentrationof nitric acid relative to hydrogen potassium peroxosulfate is adjustedto be within the range of 0.1 to 1.0 mol/l.

In the method for manufacturing the thin film transistor substrateaccording to the second embodiment, the etching agent comprising theaqueous solution containing hydrogen potassium peroxosulfate, phosphoricacid and nitric acid is used for etching the laminated film prepared bysequentially depositing the Mo or Mo alloy film and the Cu film, or thelaminated film prepared by depositing the Mo or Mo alloy films on theupper and lower faces of the Cu film, to form the gate electrode 5, thesource electrode 12, the drain electrode 14, and the lower pad layers 16a and 16 b with given patterns. As a result, the side faces of thecopper film constituting respective laminated films may be uniformlyetched, besides enabling both of the Mo or Mo alloy film and the copperfilm constituting the laminated film to be collectively etched by asimple chemical etching method such as a stationary immersion method.The Cu film and the Mo or Mo alloy film sandwiching the Cu film can besimultaneously etched when the laminated film comprises a three-layeredstructure, enabling the manufacturing yield to be good and themanufacturing process to be shortened.

Third Embodiment

The method for manufacturing the thin film transistor substrateaccording to the third embodiment of the present invention will bedescribed hereinafter.

The method for manufacturing the thin film transistor substrateaccording to the third embodiment differs from the method formanufacturing the thin film transistor substrate according to the firstembodiment in that a laminated film of a Cr or Cr alloy film and the Cufilm is formed for the laminated film for forming the gate electrode 5and the lower pad layer 16 b, a laminated film of a Cr or Cr alloy filmand the Cu film is formed for the laminated film for forming the sourceelectrode 12, the drain electrode 14 and the lower pad layer 16 a. Anetching agent comprising an aqueous solution containing hydrogenpotassium peroxosulfate and hydrochloric acid is used for etching theselaminated films.

It is preferable for allowing respective metallic films constituting thelaminated film to be etched at an approximately the same etching rate byone etching run, that the concentration of hydrochloric acid relative tohydrogen potassium peroxosulfate in the etching agent is adjusted to bewithin the range of 4 to 11 mol/l. When the substrate 2 on which thelaminated film has been formed is immersed in the etching agent foretching the laminated film, the Cu film constituting the laminated filmis effectively etched with hydrogen potassium peroxosulfate at the areanot masked with a mask pattern, and Cu in the Cu film reacts withhydrochloric acid, thereby enabling the Cr or Cr alloy film under the Cufilm to be effectively etched while forming bubbles.

When the gate electrode 5, the source electrode 12, the drain electrode14, and the lower pad layer 16 a and 16 b with given patterns are formedby etching a laminated film prepared by sequentially depositing Cr or Cralloy films and Cu films in the method for manufacturing the thin filmtransistor substrate according to the third embodiment of the presentinvention, the side faces of the copper film constituting respectivelaminated films can be uniformly etched by using an etching agentcomprising an aqueous solution containing potassium hydrogenperoxosulfate and hydrochloric acid. Moreover, since both of the Cr orCr alloy film and the copper film constituting the laminated film can becollectively etched by a simple chemical etching method such as animmersion method, a good production yield as well as a shortmanufacturing process can be attained.

While the method for etching the laminated film comprising the Ti or Tialloy film and the Cu film, the laminated film comprising the Mo or Moalloy film and the Cu film, and the laminated film comprising the Cr orCr alloy film and the Cu film have been described in the foregoing firstto third embodiments, the Cu film can be selectively etched by using anaqueous solution containing potassium hydrogen peroxosulfate as anetching agent for etching the laminated film comprising the W or W alloyfilm and the Cu film, the laminated film comprising the Ta or the Taalloy film such as TaN film and the Cu film, the laminated filmcomprising the TiN film an the Cu film, and the laminated filmcomprising the TiO_(x) film and the Cu film. Otherwise, when an aqueoussolution containing potassium hydrogen peroxosulfate is used as anetching agent for etching the laminated film comprising the Mo film andthe Cu film, it is possible to simultaneously etch the Mo film and theCu film, although the etching rate of the Mo film is smaller than theetching rate of the Cu film.

Fourth Embodiment

The method for manufacturing the thin film transistor substrateaccording to the fourth embodiment of the present invention will bedescribed hereinafter.

FIG. 4 is a partial cross section illustrating an example of the thinfilm transistor substrate manufactured by the method for manufacturingthe thin film transistor substrate according to the fourth embodiment ofthe present invention. This thin film transistor substrate 1 a differsfrom the thin film transistor substrate 1 shown in FIG. 3 in that thegate electrode 5 and the lower pad layer 16 b are composed of the Cufilm 4, and the source electrode 12, the drain electrode 14 and thelower pad layer 16 a are also composed of the Cu film 11.

The method for manufacturing the thin film transistor substrateaccording to the fourth embodiment differs from the method formanufacturing the thin film transistor substrate according to the firstembodiment in that the Cu film 4 is formed for the gate electrode 5 andlower pad layer 16 b, and the Cu film 11 is formed for the drainelectrode 14 and lower pad layer 16 a. An aqueous solution containingpotassium hydrogen peroxosulfate is used as an etching agent for theseCu films 4 and 11.

The preferable concentration of potassium hydrogen peroxosulfate in theetching agent to be used herein is within the range of 0.08 to 2.0mol/l. It is preferable that the etching agent contains acetic acid forimproving wettability on the Cu film, and the weight ratio of aceticacid in the etching agent relative to potassium hydrogen peroxosulfateis preferably adjusted within the range of 10 to 75% by weight.

When the gate electrode 5, the source electrode 12, the drain electrode14, and the lower pad layers 16 a and 16 b with given patterns areformed by etching the Cu films 4 and 11 formed on the substrate 2 in themethod for manufacturing the thin film transistor substrate according tothe fourth embodiment, an aqueous solution containing potassium hydrogenperoxosulfate is used as an etching agent. As a result, the Cu films 4and 11 can be etched by a simple chemical etching method such as astationary immersion method. Moreover, the time-dependent changes of theetching rate is small and the side faces of the Cu films 4 and 11 areuniformly etched to enable the gate electrode 5, the source electrode12, the drain electrode 14, and the lower pads 16 a and 16 b to beformed with desired line width, thereby a good manufacturing yield and asimple manufacturing process can be attained to improve themanufacturing efficiency. A low cost thin film transistor substrate istherefore obtained by improving the manufacturing yield using the methodfor manufacturing the thin film transistor substrate according to thefourth embodiment having the constructions as hitherto described.

Fifth Embodiment

FIG. 11 shows a partial cross section of the thin film transistorsubstrate obtained by the method for manufacturing the electronic devicesubstrate according to the fifth embodiment of the present invention.

The reference mark a, b and c denote a thin film transistor (TFT) part,a terminal portion (a pad portion) of a source wiring and a capacitorportion (a Cs portion), respectively. While these three portions areactually located with some distances apart one another, they areillustrated as if they are in adjacent relations one another for theconvenience of illustration.

The thin film transistor portion a will be described first.

A semiconductor layer 73 comprising polysilicon is formed on thesubstrate 2 via an insulation layer 72 in the thin film transistorportion a. A gate insulation film 74 is formed on the center of thesemiconductor layer, and a gate electrode (a first metallic layer ) 75is provided on the gate insulation film 74. The gate electrode 75 iscomposed of a Ti or Ti alloy film 43 with a film thickness of 50 to 100nm and a Cu or Cu alloy film 44 with a film thickness of 100 to 200 nm.The gate electrode 75 is integrated with a gate wiring (not shown), andan interlayer insulation film (a first insulation layer) 76 is providedon the gate electrode 75.

A source area 73 a and a drain area 73 b are formed in the semiconductorlayer 73, and the portion sandwiched with these source area 73 a anddrain area 73 b serves as a channel portion 73 c. The semiconductorlayer constituting these source area 73 a and drain area 73 b is formedso as to penetrate under the gate insulation film 74.

A source wiring (a second metallic layer) 77 is formed on the sourcearea 73 a, and a drain electrode (a second metallic area) 78 is formedon the drain area 73 b. These source wiring 77 and drain electrode 78are composed of a Ti or Ti alloy film 79 with a film thickness of 50 to100 nm and a Cu or Cu alloy film with a film thickness of 100 to 200 nm.

A passivation film 81 is formed so as to cover the entire surface, acontact hole 122 perforating through the passivation film 81 to reachthe drain electrode 78 is formed, and a pixel electrode 123 comprisingITO connected to the drain electrode 78 through the contact hole 122 isformed.

A passivation film 81 covering the gate wiring is open, similar to thecontact hole, at the gate terminal portion at the end of the gate wiringconnected to the gate electrode 75, although their illustration isomitted, and pads comprising ITO are provided to be in electricalcontinuity with the gate wiring.

With respect to the terminal portion b of the source wiring 77, aninterlayer insulation film (a second insulation film) 124 is formed onthe insulation layer 72 formed on the substrate 2, a lower pad layer 77a comprising a Ti or Ti alloy film 79 and a Cu film 80 is formed on theinterlayer insulation film 124, the passivation film 81 is formed on thelower pad, and a contact hole reaching the lower pad layer 77 a isformed.

An upper pad layer 126 comprising ITO is formed along the inner wallface and bottom face of the contact hole 125. The lower pad layer 77 ais electrically connected to an upper pad layer 126 through this contacthole 125.

With respect to the capacitor portion d, a capacitor line (a firstmetallic line) 127 comprising the Ti or Ti alloy film 43 and the Cu film44 is formed on the substrate 2 via the insulation layer 72, aninterlayer insulation film (a second insulation film) 128 is formed onthe capacitor line, a capacitor electrode (a second metallic film) 129comprising a Ti or Ti alloy film 79 and a Cu film 80 is further formedon the capacitor line, and the passivation film 81 is additionallyformed on the capacitor electrode to form a contact hole 130 reachingthe capacitor electrode 129. A layer 131 comprising ITO is formed alongthe inner wall face and bottom face of the contact hole 130. The layer131 is electrically connected to the capacitor electrode 129 through thecontact hole 130.

While the gate electrode (the first metallic layer) 75 and the capacitorline (a first metallic layer) 127 provided in the electronic devicesubstrate 71 as shown in FIG. 11 are formed by a sputtering method orphotolithographic method, the gate electrode (the first metallic layer)75 and the capacitor line (the first metallic layer) 127 can be obtainedby forming a mask with a given pattern on the surface of the laminatedfilm prepared by sequentially depositing the Ti or Ti alloy film 43 andthe Cu film 44, followed by etching the laminated film comprising the Tior Ti alloy film 43 and the Cu film 44 using an etching agent comprisingan aqueous solution containing a peroxosulfuric acid salt, hydrofluoricacid, and hydrochloric acid or a chloride, or comprising an aqueoussolution containing a peroxosulfuric acid salt and a fluoride.

While the source wiring (the second metallic layer) 77, the drainelectrode (the second metallic layer) 78, the lower pad layer (thesecond metallic layer) 77 a and the capacitor electrode (the secondmetallic layer) 129 are formed by a sputtering method and aphotolithographic method, the source wiring (the second metallic layer)77, the drain electrode (the second metallic layer) 78, pad layer (thesecond metallic layer) 77 a and the capacitor electrode (the secondmetallic layer) 129 are formed by forming a mask with a given pattern onthe surface of the laminated film prepared by sequentially depositingthe Ti or Ti alloy film 79 and the Cu film 80, followed by etching thelaminated film comprising the Ti or Ti alloy film 79 and the Cu film 80using an etching agent comprising an aqueous solution containing aperoxosulfate salt, hydrofluoric acid, and hydrochloric acid or achloride, or comprising an aqueous solution containing a peroxosulfatesalt and a fluoride.

According to the method for manufacturing the electronic devicesubstrate in the fifth embodiment, the laminated film comprising the Tior Ti alloy film 43 and the Cu film 44, or the laminated film comprisingthe Ti or Ti alloy film 79 and the Cu film 80, can be collectivelyetched without leaving any etching residues to make it possible toaccurately form the desired gate electrode (the first metallic layer)75, the capacitor line (the first metallic layer) 127, the source wiring(the second metallic layer) 77, the drain electrode (the second metalliclayer) 78, pad layer (the second metallic layer) 77 a and the capacitorelectrode (the second metallic layer) 129, thereby allowing themanufacturing process to be simplified besides improving themanufacturing yield.

FIG. 5 is an illustrative drawing showing one example of a reflectiontype liquid crystal display device provided with the thin filmtransistor substrate manufactured by the method for manufacturing thethin film transistor substrate according to the embodiment in thepresent invention.

In the reflection type liquid crystal display device (an electronicequipment), an upper transparent electrode layer 55 and an upperorientation film 57 are provided at the inner face side of an upperglass substrate 51 of upper and lower side glass substrates 51 and 52,which are in opposed relation one another by sandwiching a liquidcrystal layer 59, in the order from an upper glass substrate 51 side,and a lower transparent electrode layer 56 and a lower orientation film58 are provided at the inner face side of the lower glass substrate 52in the order from the lower glass substrate 52.

The liquid crystal layer 59 is disposed between the upper orientationfilm 57 and the lower orientation film 58. An upper polarizer 60 isprovided at the outer face side of the upper glass substrate 51, and alower side polarizer 61 is provided at the outer face side of the lowerside glass substrate 52. A reflection plate 62 is attached to the outersurface of the lower polarizer 61 with a rough surface 65 of itsreflection film 64 toward the lower side polarizer 61. The reflectionplate 62 is formed, for example, by depositing the metallic reflectionfilm 64 comprising Al or silver on the rough surface of a polyester film63 on the surface of which a randomly rough surface is formed, whichcomprises a randomly rough face 65 on the surface.

The lower glass substrate 52 corresponds to the substrate 2, and thelower transparent electrode layer 56 corresponds to the ITO layer (thepixel electrode) 19, of the thin film transistor substrate manufacturedby applying the method for manufacturing the thin film transistorsubstrate according to any one of the first to fifth embodiments.

Since the thin film transistor substrate 1 a using the copper wiring asthe low resistance wiring, or the thin film transistor substrate 1 usingthe laminated wiring comprising the copper film, is provided in thereflection type liquid crystal display device, decrease of signalvoltages and wiring retardation of signals ascribed to the wiringresistance are hardly caused, providing such advantages as readilyrealizing a display device that is most suitable for a large areadisplay that requires an long extension of wiring or a high-precisiondisplay that forces fine wiring.

EXAMPLES

Although the present invention is described in more detail withreference to the examples, the present invention is not restrictedmerely by these examples.

Example 1

An aqueous solution of Oxon (trade name, made by Aldrich Co., an aqueoussolution containing 2KHSO₅.KHSO₄.K₂SO₄) and an aqueous solution ofammonium peroxosulfate ((NH₄)₂S₂O₈) were prepared as an etching agent,and the mole concentration dependency of the etching rate of Cu when theCu film is etched using each etching agent was studied as follows.

Test pieces prepared by forming a Cu film with a film thickness of 300nm on a glass substrate were manufactured, and the etching rates whenthese test pieces were etched using the etching agents in which moleconcentrations are changed were determined. The results are shown inFIG. 6.

The results shown in FIG. 6 show that, since approximately the sameresult is obtained between the etching rate using the etching agentcomprising Oxon and the etching rate using the etching agent of thecomparative example comprising the aqueous solution of ammoniumperoxosulfate, the etching agent in the example can be used for theetching agent of the Cu film.

Example 2

The etching agent in the example comprising the aqueous Oxon solutionused in Example 1, and the etching agent in the comparative examplecomprising the aqueous ammonium peroxosulfate solution were prepared,and the film thickness distribution of the Cu film when the foregoingeach test piece was etched using respective etching agents wasinvestigated. A mask pattern with a given pattern (objective wiringwidth of 200 μm) was placed on the surface of each test piece. Theresults are shown in FIG. 7. In FIG. 7, the vertical axis corresponds tothe position μm) on the substrate where the line width is measured andthe horizontal axis, and the horizontal axis corresponds to the depthprofile (film thickness). The dot-and-broken line and the solid line inFIG. 7 denote the result of using the etching agent in the comparativeexample, and the result of using the etching agent in the example,respectively.

The results in FIG. 7 show that, when the etching agent in thecomparative example is used, the Cu film outside of the Cu wiring areais left behind and only the periphery of the mask pattern has beenetched with an abnormally rapid rate. The film is incompletely etchedand the width of the Cu wiring is about 160 μm that is by about 40 μmsmaller than the objective line width, indicating the presence ofpattern slimming phenomenon. When the etching agent in the example isused, on the contrary, no phenomenon of abnormally rapid etching at theperiphery of the mask pattern is observed besides leaving no Cu filmbehind except the wiring portion. In addition, the width of the Cuwiring is about 200 μm, showing that a Cu wiring with excellentdimensional accuracy has been formed.

Example 3

An etching agent of this example comprising 0.05 mol/l of an aqueousOxon solution (the concentration of KHSO₅ is 0.1 mol/l) and an etchingagent of the comparative example comprising 0.05 mol/l of an aqueoussolution of ammonium peroxosulfate were prepared, and the time-dependentchanges of the etching rate when each test piece was etched using eachetching agent were examined. The results are shown in FIG. 8. Theresults in FIG. 8 show that, when the etching agent of the comparativeexample is used, the etching rate severely changed with time from theday 1 to the day 4, and the time-dependent change decreases at day 4 andthereafter. When the etching agent in the example is used, on thecontrary, the etching rate showed no change from the day 1 to the day17, and the time-dependent change is small at day 17 and thereafter.

The results in the examples 1 to 3 suggest that the etching rate doesnot show any time-dependent changes to allow the amount of side-etchingof the Cu film to be uniform, enabling a copper wiring with a desiredline width to be readily obtained.

Example 4

Glass substrates, on which a laminated film prepared by depositing a Cufilm with a thickness of 100 nm is formed on various substrate films (aCr film, Ti film, Mo film, W film and TiN film) with a thickness of 50nm, were immersed in an etching agent comprising 0.05M of an aqueousOxon solution (containing 0.1 mol/l of KHSO₄) for 0.5 hour, and etchingselectivity of the substrate metal film was investigated. The resultsare listed in TABLE 1. TABLE 1 EVALUATION ITEM SELECTIVITY OF ETCHINGSUBSTRATE LAYER OF Cu Cr Ti Mo W TiN (ETHCING AGENT) x x Δ x x AQUEOUSOXON SOLUTION (KHSO₅ 0.1M)x not etchedΔ 8 nm/min (80 Å/min)

The results in TABLE 1 show that the Cr film of the laminated filmcomprising the Cr film and the Cu film, the Ti film of the laminatedfilm comprising the Ti film and the Cu film, the W film of the laminatedfilm comprising the W film and Cu film, and the TiN film of thelaminated film comprising the TiN film and the Cu film were all notetched when the 0.05M aqueous Oxon solution was used as the etchingagent. It was also revealed that the Mo film in the laminated film ofthe Mo film and the Cu film was etched in a rate of 8 nm/min. The Cufilm in all the laminated films was etched at a rate of 160 nm/min whenthe Cu film with a thickness of 300 nm was used in the laminated film.

Example 5

A test piece was prepared by depositing a Cu monolayer film with athickness of 300 nm on a glass substrate by a sputtering method or aphotolithographic method, and the test piece was etched using an etchingagent comprising an aqueous solution containing HF, ammoniumperoxosulfate [(NH₄)₂S₂O₈] and HCl (the concentration of HF was 0.2% andthe concentration of (NH₄)₂S₂O_(8 was) 2%). The HCl concentrationdependency of the etching depth of the Cu film was investigated bychanging the HCl concentration in the etching agent in a range of 0% to0.5%. The results are shown in FIG. 12.

The results in FIG. 12 show that, when the test piece on which the Cumonolayer film was formed was etched using an etching agent comprisingan aqueous solution containing HF, ammonium peroxosulfate [(NH₄)₂S₂O₈]and HCl, the etching rates were about 300 nm/min at a HCl concentrationof 0.5% and about 130 nm/min at a HCl concentration of 0%, indicatingthat the etching depth increases as the HCl concentration (the Cl⁻ ionconcentration) increases.

It was also shown that the etching depth increases as the HClconcentration (the Cl⁻ ion concentration) increases, even when anetching agent containing KCl or NH₄Cl instead of HCl is used.

The results above show that the etching rate of the Cu monolayer filmcan be increased when the Cl concentration in the etching agentcomprising an aqueous solution containing a peroxosulfate salt,hydrofluoric acid and hydrochloric acid is increased.

Example 6

A test piece on which a Ti monolayer film with a film thickness of 50 nmwas deposited on the surface of a glass substrate by a sputtering methodor a photolithographic method was prepared, and the test piece wasetched using an etching agent comprising an aqueous solution containingHF, ammonium peroxosulfate [(NH₄)₂S₂O₈] and HCl (the concentration of HFis 0.2% and the concentration of (NH₄)₂S₂O_(8 is) 2%). The HClconcentration dependency of the etching-off time (the time intervalbefore etching is completed) was investigated by changing the HClconcentration in the etching agent within a range of 0% to 0.5%. Theresults are shown in FIG. 13.

The results in FIG. 13 show that the etching rate remains approximatelyconstant since the etching-off time did not shown any change by thechange of the HCl concentration, when the test piece on which the Timonolayer film had been formed was etched using the etching agentcomprising the aqueous solution containing HF, ammonium peroxosulfate[(NH₄)₂S₂O₈] and HCl. This is because, when a wiring comprising the Timonolayer film is deposited by a sputtering method and photolithographicmethod, a TiO_(x) film with a thickness of about 2 to 5 nm, which can behardly etched, has been formed on the surface of the wiring to diminishthe etching rate.

Example 7

A test piece was prepared by depositing a laminated film comprising a Tifilm with a thickness of 50 nm and a Cu film with a thickness of 100 nmon a glass substrate by a sputtering method or a photolithographicmethod. This test piece was etched using an etching agent comprising anaqueous solution containing HF, ammonium peroxosulfate [(NH₄)₂S₂O₈] andHCl (the concentration of HF is 0.2% and the concentration of(NH₄)₂S₂O_(8 is) 2%), and the HCl concentration dependency of theetching-off time (the time interval before completing etching) of thelaminated film comprising the Ti film and the Cu film was investigatedby changing the concentration of HCl within a range of 0% to 0.5%. Theresults are shown in FIG. 14. The Ti film on the laminated film and theCu film thereon was continuously deposited by the sputtering methodwithout exposing to the air.

The results in FIG. 14 show that, when the test piece on which thelaminated film comprising the Ti film and the Cu film had been formedwas etched using the etching agent comprising the aqueous solutioncontaining HF, ammonium peroxosulfate [(NH₄)₂S₂O₈] and HCl, theetching-off time is reduced as the concentration of HCl (theconcentration of Cl⁻ ion) is increased, or the etching rate isincreased.

The results in FIGS. 12 to 14 show that, while the time required foretching a Cu monolayer film to a depth of 100 nm is about 24 seconds,and the etching-off time of the test piece on which a Ti monolayer filmwith a thickness of 50 nm is formed is about 90 seconds, the etching-offtime of the test piece on which the laminated film was formed bycontinuously depositing the Ti film with a thickness of 50 nm and the Cufilm with a thickness of 100 nm is about 30 seconds. Accordingly, theaqueous solution containing HF and ammonium peroxosulfate [(NH₄)₂S₂O₈]allows the etching-off time required for etching the Ti monolayer filmto be largely shorter than the etching-off time required for etching thelaminated film comprising the Ti film and the Cu film, and the yesypiexe is etched with an etching rate close to the etching rate foretching the Cu monolayer film. Etching in a short period of time ispossible in this case because the laminated film is not exposed to theair before depositing the Cu film in the continuous deposition of the Tifilm and the Cu film, forming no TiO_(x) film on the surface of the Tifilm.

Accordingly, when the aqueous solution of HF, ammonium peroxosulfate andHCl is used for the etching agent of the laminated film comprising theTi film and the Cu film, the laminated film is collectively etchedwithout leaving any etching residues to make it possible to form alaminated wiring having a desired line width with high precision,thereby enabling the manufacturing process to be simplified and themanufacturing yield to be improved.

Example 8

A test piece was prepared by depositing a laminated film comprising a Tifilm (a substrate layer) with a thickness of 50 nm and a Cu film with athickness of 100 nm on a glass substrate by a sputtering method or aphotolithographic method. This test piece was etched using an etchingagent comprising an aqueous solution containing KF or MH₄F, 3% of Oxon(made by Aldrich Co., an aqueous solution containing2KHSO₅.KHSO₄.K₂SO₄), and the KF or NH₄F, and concentration dependency ofthe etching-off time (the time interval before completing etching) ofthe laminated film comprising the Ti film and the Cu film wasinvestigated by changing the concentration of KF or NH₄F within a rangeof 0% to 0.5%. The results are shown in FIG. 15. The Ti film on thelaminated film and the Cu film thereon was continuously deposited by thesputtering method without exposing to the air.

The results in FIG. 15 show that the test piece on which the laminatedfilm comprising the Ti film and the Cu film has been formed can beetched using the etching agent comprising the aqueous solutioncontaining KF or NH₄F, and 3% of Oxon. The etching-off time is reducedas the KF or NH₄F concentration (the F⁻ ion concentration) increases,showing no etching residues as well as high etching rate. Collectiveetching of the laminated film comprising the Ti film and the Cu film ispossible when the etching agent contains F⁻ ion other than aperoxosulfate salt, even when the etching agent does not contain HF.

Example 9

A test piece was prepared by depositing a Cu monolayer film with athickness of 300 nm on a glass substrate by a sputtering method or aphotolithographic method. This test piece was etched using an etchingagent comprising an aqueous solution containing KF or HF, and 3% of Oxon(trade name, made by Aldrich Co., and aqueous solution containing2KHSO₅.KHSO₄.K₂SO₄) (the concentration of HF is 0.2% and theconcentration of (NH₄)₂S₂O₈ is 2%), and the relations between theetching time and the etching depth of the Cu monolayer film wereinvestigated when the concentration of KF in the etching agent waschanged within a range of 0.1% to 0.5%, and when HF was used instead ofKF. The results are shown in FIG. 16.

The results in FIG. 16 show that the etching rate for etching the testpiece on which the Cu monolayer film is formed is higher when theetching agent contains KF than when the etching agent contains HF.Together with the fact that the etching rate turns out to be higher whenthe KF concentration in the etching agent is 0.5% than when the KFconcentration in the etching agent is 0.1%, it is evident that thelarger KF concentration (F⁻ ion concentration) results in better etchingefficiency.

It is also evident that the etching rate may be more readily controlledwhen the etching agent contains HF, although the etching rate is lower,than when the etching agent contains KF.

As hitherto described in detail, the etching agent for copper comprisingan aqueous solution of potassium hydrogen peroxomonosulfate according tothe present invention allows the Cu film to be etched by a simplechemical etching method such as a stationary immersion method with notime-dependent change of the etching rate as well as with a uniformamount of side-etching of the Cu film, thereby making it possible toobtain a copper wiring with a desired line width.

1-3. (canceled)
 4. An etching agent for a laminated film of a titaniumfilm and a copper film comprising an aqueous solution containingpotassium hydrogen peroxomonosulfate and hydrofluoric acid.
 5. Anetching agent for a laminated film of a molybdenum film and a copperfilm comprising an aqueous solution containing potassium hydrogenperoxomonosulfate, phosphoric acid and nitric acid.
 6. An etching agentfor a laminated film of a chromium film and a copper film comprising anaqueous solution containing potassium hydrogen peroxomonosulfate andhydrochloric acid.
 7. An etching agent for a laminated film of atitanium film and a copper film comprising an aqueous solutioncontaining a peroxomonosulfate salt, hydrofluoric acid, and hydrochloricacid or a chloride.
 8. An etching agent for a laminated film of atitanium film and a copper film comprising an aqueous solutioncontaining a peroxosulfate salt and a fluoride.
 9. An etching agent fora laminated film of a titanium film and a copper film according to claim7, wherein said peroxosulfate salt comprises any one or more compoundsselected from KHSO₅, NaHSO₅, K₂S₂O₈, Na₂S₂O_(8 and (NH) ₄)₂S₂O₈.
 10. Anetching agent for a laminated film of a titanium film and a copper filmaccording to claim 7, wherein said chloride comprises an alkali metalchloride or ammonium chloride.
 11. An etching agent for a laminated filmof a titanium film and a copper film according to claim 8, wherein saidperoxosulfate salt comprises any one or more compounds selected fromKHSO₅, NaHSO₅, K₂S₂O₈, Na₂S₂O_(8 and (NH) ₄)₂S₂O₈.
 12. An etching agentfor a laminated film of a titanium film and a copper film according toclaim 8, wherein said fluoride comprises an alkali metal fluoride orammonium fluoride. 13-16. (canceled)